Bin level switch



Oct. 21, 1952 C. w. McM -1 2,615,102

BIN LEVEL SWITCH Filed Sept. 25, 1950 2 swears-4mm 1 CHARLES IL/ MfMnr/lIN V EN TOR.

ATTORNEY Oct. 21, 1952 c. w. MCMATH 2,615,102

BIN LEVEL SWITCH V. H 1 Filed Sept. 25, 195.0 2 SHEETS-SHEET 2 CHARLES WM9MATH INVENTOR.

AT T ORNE V Patented Oct. 21, 1952 UNITED STATES PATENT OFFICE f BINLEVEL SWITCH Charles W. McMath, Fort Worth, Tex; I Application September25, 1950, Serial No. 186,663

, 6 Claims. 1

This invention relates to switches and more particularly to pressureswitches.

In many applications pressure responsive switches are employed toindicate or warn when a tank or bin is filled to a predetermined level.For example, such switches are employed to give warning when a gravelbin is filled with gravel to its capacity. The switches may also beemployed to stop operation of loading equipment, which fills the binwith the gravel or other material, when the bin is filled to a certainlevel. Such switches should be adjustable in order that they may beadjusted to operate properly when attached to tanks or bins filled withdifferent materials which exert different pressures on the switches.Moreover, the switches should be easily assembled and disassembled tofacilitate maintenance and should be rugged in construction to withstandrough usage to which they are subjected.

Accordingly, it is an object of my invention to provide a new andimproved. switch.

It is another object of my invention to provide a new and improvedpressure responsive switch. It is another object of my invention toprovide a new and improved pressure responsive switch for use with tanksor bins to indicate when the tank or bin is filled or emptied. I

It is still another object of my invention. to provide a new andimproved pressure responsive switch having a diaphragm which issubjected to a very narrow range of movement.

Briefly stated, my new and improved pressure responsive switch comprisesa base section adapted to be connected to a tank, bin or otherreceptacle r conduit and extend through an aperture in a wall thereof. Adiaphragm is secured to the base section and has an inner surfacesubjected to the pressure exerted by the material or substance containedin the tank, bin or conduit.- In order to protect the diaphragm, abacking plate is provided which abuts the outer surface of thediaphragm. A mechanical linkage connects the backing plate to amicro-switch. An adjustable spring is operatively associated with thelinkageto providea means selectively to vary the pressure to which thediaphragm must be subjected to actuate the micro-switch.

For abetter understanding of my-invention, r'eference may-be had to thefollowing description taken in connection with the accompanying drawingand its scope will be pointed out in the appended claims. I

Figure. 1 is a sectional view of the switch shown in itsoperationalenvironment;

ing flange l3, integral with and at one endof,

central portion II, is provided with a plurality of spaced aperturesthrough which are adapted to extend screws M which engage in suitabletapped holes in wall [2. An annular resilient gasket 15 of rubber orother suitable material is interposed between flange l3 and wall l2.Gasket i5 is provided with a plurality of spaced apertures whichregister with the apertures in flange l3 and wall I 2.

An inwardly extending annular flange 16in tegral with and at the otherend of central portion H is provided with an inner bevel surface I! anda plurality of spaced threaded apertures l8 between central portion Hand beveled surface H. A diaphragm clamping ring I9 is alsoprovided witha beveled surface 20 which cooperates with beveled surface I! to securea disc shaped diaphragm 2| to flange l6 of base section l0. Ring 19 issecuredto flange It by screws 22 which extend through suitable apertures23 in ring [9 and engage threaded apertures 18 of flange l6. Ring l9 andflange l6 cooperate to maintain the central portion of diaphragm 2| in aplane normally parallel to the outer surfacev 24 of flange I6. Diaphragm2| may be made of a relatively stiff or slightly yielding material suchas reinforced rubber, or a metal sheet of brass, copper, steel or othersuitable material since very little diaphragm movement isneeded innormal operation of the device.

, The complementary beveled surfaces [1 and 20 of the flange l6 andring, l9, respectively, are

effective to create the required uniform tension on the diaphragm 2|during its installation and to maintain such tension subsequent toinstallation.

A disc shaped cover plate 25 is secured to base section ID by means ofscrews 26 which extendthrough suitable apertures in plate 25 and engagein threaded holes 21 in base section 10. A supporting block28 havingspaced legs 29and 30 is securedtoplate 25 by a screw 3| which ex tendsthrough a suitable aperture in plate .25

and engaging in a threaded hole 32 in the upper end of block 28. A lever33 is pivotally secured between legs 29 and 30 by means of a pin 34which extends through registering apertures 35, 36 and 31 in legs 29, 30and lever 33, respectively.

A ribbed backing plate 38 is secured to the free end of lever 33 bymeans of a screw 39 which extends through central apertures in backingplate 38 and a spacing sleeve 40 and engages in a threaded aperture 4|in lever 33. The upper end of screw 39 is spaced a very short distancefrom cover plate 25 to limit the movement of backing plate 38, andtherefore of diaphragm 2 I, toward cover plate 25. Also secured totheinner surface of cover plate is a spring supporting block 42 which issecured to plate 25 by a screw 43. Block 42 is provided with a slot inwhich is rigidly secured, by soldering or any other conventional means,one end of a leaf spring 44. The free end of leaf spring 44 abuts andbears against lever 33 yieldingly to urge the free end of lever 33 awayfrom cover plate 25. An adjusting screw 45 extends through a threadedaperture in cover plate 25 and bears against spring 44 to vary the forcespring 44 exerts on lever 33. A look nut 46 is provided for screw 45 tolock it in a desired position.

Intermediate its ends, lever 33 is provided with a threaded aperture inwhich is engaged a screw 41 which is disposed to engage the push rod 48of a conventional micro-switch 49 when lever 33 is moved pivotallytoward plate 25. The microswitch 49 is secured in a housing comprisingsections 50 and by means of pins 52 and 53- which extend throughsuitable apertures in sections 50, 5| and micro-switch 54. The housingsections 50 and 5| are secured to each other by means of bolts 55. Eachsection 50 and 5| is provided with a flange 56 provided with a pair ofapertures through which extend screws 5| which engage in threaded holes58 in cover plate 25'to secure the sections 5|! and 5| to plate 25.Cover plate 25 is also providedgwith an aperture 59 through which extendin telescoped relation the push rod 48 of micro-switch 43 and its sleeve36. The housing sections 50 and 5| are provided with apertures 8! and 62through one of which may extend the conductors 63 and 64 which areconnected to micro-switch 49. Conductors 63 and 64 may be connected toany suitable electric circuit to control a warning or indicating device,a motor; or any other desired electricall controlled element Inoperation, the above described pressure responsive'switch is preferablysecured to a vertical wall i2 of a tank, bin or conduit which wall maybe vertical or any slope greater than the angle of repose of thematerial in the bin, or the like. When the bin or the like is filled tosuch av height with material that thematerial abuts and exerts a forceon diaphragm 2|, the dia-' phragm 2| will yield inwardly toward plate 25provided that the force exerted. by the material,

on diaphragm 2| overcomes the force exerted by spring 44 on lever33 aswell as the force needed to flex diaphragm 2| and actuate micro-switch49; t will be obvious that screw 45 will be employed to make the spring44 exert an appropriate pressure on lever 33. When diaphragm 2| yieldsand moves, backing plate 38 will also move pivoting lever 33 towardplate 25. During this movement of lever 33, screw 4'! will, move pushrod 48 to actuate micro-switch 42': to make or break an electriccircuit. The pivotal movement of lever" 33 is limited since screw 39will abut plate 25 after lever 33 has moved a predetermined distance.When the material in the bin falls to a level in which it no longerexerts sufiicient pressure on diaphragm 2|, the force exerted by spring44 will move backing plate 38 to its original position illustrated inFigure 1. Diaphragm 2| will move back to its original position due toits resiliency.

It will be noted that diaphragm 2| does not extend, inwardly beyondflange 6 of base section l0 so that the material in the bin does not liein the path of movement of the material to impede its movement and atthe same time increase the abrasive wear of diaphragm 2|. Moreover, the.method of securing diaphragm 2| to base section, l0. obviates the needfor bolt holes which would weaken the diaphragm 2|. The backing plate 38protects diaphragm 2| from excessive force such as might result from thefalling of rocks against diaphragm 2| in gravel bin installations.

The mechanical linkage is very simple, having only one pivot thusreducing friction losses to a minimum. In addition, the range ofmovement of diaphragm 2| is quite narrow permitting the use of arelatively taut diaphragm which eliminates sagging and the resultingtendency of, the diaphragm to trap or hold material in a hollow or foldcaused by the sagging.

The arrangement and connection of parts of the above described pressureresponsive switch Base facilitates installation and maintenance. sectionI 0 can be secured to wall l2 from the outside of the bin thus obviatingthe necessity of having access to the interior of the bin. Themicro-switch 49 can be removed for inspection, repair or replacementwithout disturbing the other components of the system since screw 41merely bears against push rod 48 of the switch. Should adjustment orrepair of the mechanical linkage be necessary, cover plate 25 only needbe removed since diaphragm 2| is not connected to backing plate 38 orany part of the mechanical linkage.

While I have described and illustrated a preferred embodiment of myinvention, it will be obvious that various changes and modifications canbe made without departing from my invention and I, therefore, aim in theappended claims to cover all such changes and modifications as !allwithin the true spirit and scope of myinvention.

What is claimed is l. A pressure responsive device comprising a hollowbase section; a resilient diaphragm secured to said base section andclosing of! one end of said base section; a cover plate secured to saidbase section and closing off the other end of said base section; abacking plate movably disposed in said base section and abutting saiddiaphragm; a lever. having one end pivotaily connected to' said cover,plate and the other end secured-tosaid'backing plate; means biasingsaidbacking plate toward said diaphragm;- astop operatively associated withsaid backing plate for limiting movement of said backing plate towardsaid cover plate; and a switch mounted on said cover plate exteriorly ofsaid base section, said cover platebeing provided with an aperture, saidswitch having an operatin member extending through said aperture intosaid base section, said operating member being operatively associatedwith said backing plate and responsive to movement of said backing platetoward said cover plate.

- 2. A pressure responsive device comprising a hollow base section; aresilient diaphragm se cured to said base section and closing on one endof said base section; a cover plate secured to said base section andclosing oiT the other end of said base section; a backing plate movablydisposed in said base section and abutting said diaphragm; a leverhaving one end pivotally connected to said cover plate and the other endsecured to said backing plate; means biasing said backing plate towardsaid diaphragm; a stop operatively associated with said backing platefor limiting movement of said backing plate toward said cover plate; anda switch mounted on said cover plate exteriorly of said base section,said cover plate being provided with an aperture, said switch hav ing anoperating member extendin through said aperture into said base section,said operating member being operatively associated with said lever andresponsive to pivotal movement of said lever toward said cover plate.

3. A pressure responsive device comprising a hollow base section; aresilient diaphragm secured to said base section and closing on one endof said base section; a backing plate movably disposed in said basesection and having one side abutting one side of said diaphragm, saidbacking plate substantially closing off said one end of said basesection; a cover plate secured to said base section and closing off theother end of said hollow base section; a switch mounted on said coverplate exteriorly of said base section, said cover plate being providedwith an aperture, said switch havin an operating member extendingthrough said aperture into said base section; a lever pivoted at one nedto said cover plate and connected at its opposite end to the center ofsaid backing plate and having engagement with said operating member foractuating said switch upon movement of said backing plate toward saidcover plate, means biasing said backing plate toward said diaphragm andmeans for adjusting the tension on said biasing means.

4. A pressure responsive device comprising a hollow base section havingan internally beveled flange on one end, a ring attached to the interiorof said flange having a bevel corresponding to the bevel of said flange;a resilient diaphragm having its perimeter secured between the bevels ofsaid ring and flange and closing off one end of said base section; abacking plate movably dis posed in said base section and having one sideabutting one side of said diaphragm, said backing plate beingsubstantially equal in diameter to the diameter of the effective area ofsaid diaphragm; a cover plate secured to said base section and closingoff the other end of said hollow base section; a switch mounted on saidcover plate exteriorly of said base section, said cover plate beingprovided with an off-center aperture, said switch having an operatingmember extending through said aperture into said base section; a pivotedlever connecting said backing plate and said operating member foractuating said switch upon movement of said backing plate toward saidcover plate; and means operatively associated with said lever forbiasing said backing plate away from said cover plate.

5. In a pressure responsive device: a base section having a centralaperture provided with an internally beveled flange, a ring having abevel confronting the bevel of said flange, a resilient diaphragmsecured at its perimeter between said ring and flange and closing offsaid central aperture at one end of said base section; a backing platemovably disposed in said base section relative to said central apertureand abutting said diaphragm, said backing plate having substantially thesame radius as the effective area of said diaphragm; a cover platesecured to said base section and closing off said central aperture atthe other end of said base section; a switch mounted on said cover plateexteriorly of said base section, said cover plate having an oil centeraperture, said switch having an operating member extending through saidaperture into said central aperture of said base section, a pivotedlever connecting said operating member and said backing plate foractuating said switch upon movement of said backing plate toward saidcover plate and means for biasing said backing plate toward saiddiaphragm.

6. The device of claim 5, and a stop means operatively associated withsaid backing plate for limiting movement of said backing plate towardsaid cover member.

CHARLES W. MCMATH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 993,977 Frasier May 30, 19111,379,803 Covert May 31, 1921 2,441,480 Francis May 11, 1948 FOREIGNPATENTS Number Country Date 352,144 Great Britain July 9, 1931

